1. Field of the Invention
This invention relates to a novel liquid crystal substance exhibiting liquid crystal phases within a broad temperature range, a good stability and a low viscosity.
2. Description of the Related Art
Liquid crystal display elements utilize the optical anisotropy and dielectric anisotropy of liquid crystal substances, and are classified into those of various modes such as TN mode (Twisted Nematic mode), DS mode (Dynamic Scattering mode), guest-host mode, DAP mode, etc. depending upon their display modes, but their properties suitable to the respective uses thereof are different. It is, however, common to any of liquid crystal substances that they must to be stable to moisture, air, heat, light, etc., and further, they should exhibit liquid crystal phases within a temperature range as broad as possible, and also should have optimum dielectric anisotropy values varied depending upon the kinds of display elements.
At present, however, there is no single compound satisfying all of such requirements, but it is the present status that liquid crystal compositions obtained by blending several kinds of liquid crystal compounds or non-liquid crystal compounds have been used. Recently, display elements operated over a range from low temperatures (about -40.degree. C.) to high temperatures (about 80.degree.-90.degree. C.) have come to be particularly required; thus liquid crystal compositions having superior operating characteristics within a broader temperature range have been desired.